Materials Needed:

  1. 1Pre-Mixed Stain (1/2 pint)
  2. 2Mineral Spirits (4 fl. Oz.)
  3. 3Top Coat/Sealer (20 fl. Oz.)
  4. 4Two Clean Cloths
  5. 5One Pair Protective Gloves
  6. 63'' China Bristle Brush
  7. 7Two Stir Sticks
  8. 8Finishing Instruction
  9. 9Artist brush
  10. 10Brown or black paint marker

How-to Guide: Stain Knots on a Plastpro Knotty Alder Door

Step 1: Surface Preparation

  1. Lay door horizontally on saw horses or a table.

  2. Remove all hardware and mask off anything you don’t want stained, such as the glass insert.

  3. DO NOT SAND GRAINED FIBERGLASS.

  4. Wipe the door with mineral spirits to clean any dust or residue from the surface. Allow door surface to dry completely before applying stain.

*FOR BEST STAIN RESULTS, please make sure temperatures are between 50°F - 90°F, humidity below 85%, do not stain in direct sunlight, and do not stain or apply top coat when dew is present.

Step 2: Identify The Knots

  1. Look for the cracks and swirl marks on the doors.

  2. Identify how many knots you would like to accentuate.

NOTE: Before you apply stain to the door, please review all the methods used to create the knots in Step 4. Method 3 will require you to fill in the cracks before applying stain to the door.

Step 3: Apply The Stain To The Door

  1. Starting at the center of the door, stain one to two panels at a time. Apply stain with a 3” to 4” soft bristle brush, or rag. Apply enough stain to fill the door grain. (Refer to the door staining diagram.)

  2. With a clean, lint-free 24 x 24 inch cloth, softly wipe the surface until you reach your desired tone.
    TIP: When the rag becomes saturated with stain, re-fold to work with a less-saturated section. Be sure to use the same rag for the whole door.

  3. After all the stain is brushed evenly, you may add finishing touches by using a small 1” to 2” brush or cotton swabs.

Second Coat (if desired)

Allow the door to dry for at least 48 hrs between coats. Repeat as above.

Step 4: Create The Knots

Method 1 – Foam brush

  1. First, darken the cracks using the foam brush. Dip the foam brush gently in the stain, brush off the excess on the side of the can and apply directly onto the crack. Darkening the crack creates contrast against the finish of the door and will help the door achieve the look of real wood.

  2. Use the bristle brush to create a circular shape around the crack.

  3. To create a lighter stain knot, wait 10-15 minutes and gently wipe off any excess stain with the kit’s cloth.

  4. To create a darker stain knot, wait for the current layer of stain to dry, and then apply more stain with the kit’s cloth. Dip the cloth gently in the stain, and apply thin layers in circular motions by following the swirl graining around the crack. Allow each layer to dry before applying a new layer. Repeat this process until you have reached your desired shade.

Method 2 – Artist brush

  1. Darken the cracks using an artist brush. Dip the artist brush gently in the stain, brush off the excess on the side of the can and apply directly onto the crack. A brush with a finer tip will allow more precise strokes.

  2. Use the bristle brush to create a circular shape around the crack.

  3. To create a lighter stain knot, wait 10-15 minutes and gently wipe off any excess stain with the kit’s cloth.

  4. To create a darker stain knot, wait for the current layer of stain to dry, and then apply more stain with the kit’s cloth. Dip the cloth gently in the stain, and apply thin layers in circular motions by following the swirl graining around the crack. Allow each layer to dry before applying a new layer. Repeat this process until you have reached your desired shade.

Method 3 – Paint marker

TIP: With this method, you will have to fill in the cracks first with the paint marker, and then apply stain to the door.

  1. Use a brown paint marker on lighter finished doors (Early American, Spanish Oak) and a black paint marker on darker finished doors (Mahogany, Moorish Teak and Charcoal).

  2. Fill in cracks accordingly to preference.

  3. Use the bristle brush to create a circular shape around the crack.

  4. To create a lighter stain knot, wait 10-15 minutes and gently wipe off any excess stain with the kit’s cloth.

  5. To create a darker stain knot, wait for the current layer of stain to dry, and then apply more stain with the kit’s cloth. Dip the cloth gently in the stain, and apply thin layers in circular motions by following the swirl graining around the crack. Allow each layer to dry before applying a new layer. Repeat this process until you have reached your desired shade.

Step 5: Protective Top Coat

Application of polyurethane top coat with UV inhibitors like ZAR™ Exterior polyurethane, Wood Kote® Flagship UV, or Minwax® Fast Drying Polyurethane for exterior applications.

  1. After stain has completely dried (48 hours), mix the top coat well and apply evenly using a clean dry 2” soft bristle brush or 3” foam brush. Be sure to stop when the grain changes direction.

  2. Apply two or three coats of finish, allowing at least 24 hours of drying time between each application.

Normal Maintenance

Even a well-finished fiberglass door will be affected by exposure and weathering from sun, moisture, and air pollutants. It is considered normal maintenance to re-apply the topcoat approximately every two years. 

Due to the variability in finishing materials, application conditions and techniques, all of which are beyond the control of Plastpro . Plastpro cannot be responsible for the performance of field applied finishes or individual application techniques. 

*Staining instructions are for Oil-Based, Premium Quality Wood Stains or similar product designed for use on a fiberglass surface. Please note the instructions indicated are specific to the Zar brand stain included in our stain kit. Please reference stain manufacturers instructions before applying any stain.